In-situ product removal of p-coumaric acid at DTU Kemiteknik

1.5 billion Smartphones are sold every year, which would correspond to every Dane buying 7 a day. All these smart devices use LCD screens, which currently contain silicon transistors. These could be replaced by organic transistors, also offering new properties such as flexibility for the development of wearable devices. Organic transistors based on poly(4-vinylphenol) could be produced sustainably from renewable sugars, with the help of microorganisms (see figure). However, the production titers of the chemical precursor p-coumaric acid (pCA) that have been achieved through the microbiological route are insufficient for the process to be economically viable. One possible solution to increase the production titers is to utilize in-situ product removal (ISPR), where the product is removed from the fermentation broth as it is being produced, in order to limit product toxicity towards the production host and product inhibition towards the tyrosine ammonia lyase (TAL) enzyme, which catalyzes pCA production. Previous analyses into ISPR of pCA did not properly take into account the improved activity of TAL at alkaline pH. The development of a method for ISPR of pCA at alkaline pH is the aim of the project. 

Some of the factors influencing the choice of a suitable method for ISPR of pCA include the low solubility of pCA in water, the variable electrical charge of pCA dependent on the pH, and the presence of cells and other chemicals in the fermentation broth. An initial analysis has yielded several possibilities including extraction with ion-exchange resin or with an aqueous two-phase system, but the student is expected to make their own analysis and decide on the most promising methods to test. The student will test these methods experimentally for their ability to remove pCA and the substrate tyrosine from an aqueous solution across a range of pH, their biocompatibility with growing and resting microbial cells, and finally their ability to remove pCA in-situ.  Further development of the method could include practical implementation in a bioreactor, recovery of pCA after its' removal, and recycling of any chemicals or materials used. The student is expected to be studying a relevant study line and have an interest in downstream processing, process development, fermentation. Some practical laboratory experience would be an advantage.

 

Remember that a project is an invitation for dialogue where you agree on the focus of the project. You have the possibility to suggest other problem statements and perspectives besides what is outlined in the project description. Read more about project collaborations in Career guide